Fix a bad merge in pkg/stack_trace.
Fix a bad merge in pkg/stack_trace.

TBR
R=rnystrom@google.com

Review URL: https://codereview.chromium.org//22880030

git-svn-id: 23a8f5f0d54e45b03616c23fdace24df99c52d8d@26467 260f80e4-7a28-3924-810f-c04153c831b5

dart-lang/stack_trace